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Date: Wed, 29 Jul 2009 19:02:20 +0300
From: Andriy Gapon <avg@freebsd.org>
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To: Thomas Backman <serenity@exscape.org>
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Cc: freebsd-fs@freebsd.org, FreeBSD current <freebsd-current@freebsd.org>,
	Pawel Jakub Dawidek <pjd@freebsd.org>
Subject: Re: zfs: Fatal trap 12: page fault while in kernel mode
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on 29/07/2009 17:36 Andriy Gapon said the following:
> on 29/07/2009 17:10 Thomas Backman said the following:
> [snip]
>> (kgdb) fr 11
> [snip]
>> (kgdb) p *sx
>> $8 = {lock_object = {lo_name = 0xffffffff80b5634c "zp->z_lock", lo_flags
>> = 40894464 [0x2700000, btw], lo_data = 0, lo_witness = 0x0},
>>   sx_lock = 6}
>>
>> ... as you might notice, I'm mostly clueless as to what I'm doing here. :o
>> Hope that helps (a bit), though.
> 
> Yes, it does and a lot.
> sx_lock = 6 means that this sx lock is destroyed:
> #define SX_LOCK_DESTROYED                                               \
>         (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)
> 
> And lo_name tells that this is zp->z_lock.
> This lock is destroyed in zfs_znode_cache_destructor.
> Not enough knowledge for me to proceed further.

So I guess that this is a case when zfs_znode_delete() was called on znode that
was still referenced from some vnode. When the vnode gets reclaimed we get this
problem.
Could you please examine vp in frame 15 or 16?

-- 
Andriy Gapon